Copyright  2000 by ASME 1 FEDSM2000 FORUM ON FLUID MEASURENMENT AND INTRUMENTATION BOSTON, MASSACHUSETTS, ON JUNE 11-15, 2000 FEDSM2000-11115 DESIGN OF A FLOW DEFLECTOR FOR AN ACCURATE FLOW METER CALIBRATION FACILITY C. Corrales-Barallobre G. Polanco Department of Mechanics Department of Mechanics Universidad Simón Bolívar Universidad Simón Bolívar R. Martínez-Huen L. Rojas-Solórzano Department of Mechanics Department of Energy Conversion Universidad Simón Bolívar Universidad Simón Bolívar L. Alvarez Lab. Tech. Supervisor Universidad Simón Bolívar ABSTRACT The design and test of a flow deflector gate used for controlling the flow deviation toward the primary tank in a flow-meter calibration facility is presented. The deflector gate is pneumatically controlled and permits the flow conduction to either the suction tank or to the primary tank. The deflector is designed to approximately compensate the flow deficit towards the primary tank during the opening, with the flow excess while in the shutting process. Numerical simulations are performed to study the flow hydrodynamics during the deflector operation. Results are compared to experimental data, and used to improve the gate design. The enhanced design proved to guarantee the uniformity of the flow through the calibration section and the dramatic reduction of the error in volume measurement during calibration. INTRODUCTION The degree of precision, using a primary tank, to determine the flow rate discharge out of a pipeline, is directly related to the measurement of the volume and period of time taken to download the volume into the tank. This paper presents the design and evaluation of a derivation gate, which diverts the flow to a primary tank, volumetrically calibrated to measure the volume stored during the discharge interval of time. During the gate operation, a fraction of the diverted volume is accounted at opening, while another fraction is taken at closing. These two fractions, ideally speaking, though included in the period of time of the measurement, do not correspond to volume through the pipeline in steady regime. Nevertheless, while opening the gate, the deficit in volume accounted for, tends to be compensated by the excess obtained when closing it. Therefore, in order to accurately compute the flow discharge through the diverting gate, it is very important to perform a thorough analysis of the hydrodynamic behavior of the gate during its opening and closing cycles. The error in flow-rate measurement through the whole process, related to the gate operation, is presented as a function of the diverted volume and time. Results from a preliminary numerical analysis of the flow through the gate at different positions permitted to foresee the gate behavior and to develop a close to optimal design of it. A comparison between numerical predictions and experimental results is also presented. DESCRIPTION OF THE SYSTEM The derivation gate consists in a 0.5m x 0.6 m steel plate pivoting along one side, while activated by a pneumatic actuator that allows it to carry out an angular motion between 0 and 14° (Fig. 1). The gate is part of a reception manifold to which four pipelines (8”, 10”, 12” and 14”) of the Universidad Simón Bolívar Flowmeter Calibration Facility (USB-FCF) are connected.